#36520: Performance Regression in parse_header_params
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Reporter: David Smith | Owner: (none)
Type: Bug | Status: new
Component: HTTP handling | Version: dev
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Natalia Bidart):
So! I followed the suggestion from the Python Discourse post, where Barry
Scott suggested to benchmark *bytes* header parsing instead of unicode
since:
> When I worked on code to parse HTTP headers we worked in bytes to save
the cost of decoding to unicode.
And I was surprised to see that the slowdown is actually a speed gain for
complex headers. See these comparison tables:
||= Python 3.11 (real `cgi`, email.message gets `bytes`) =||= `cgi` =||=
`email.message` =||= ratio =||
|| `text/plain` || 0.316 ||
1.618 || ~5.1x ||
|| `text/html; charset=UTF-8; boundary=something` || 1.362 ||
4.364 || ~3.2x ||
|| `application/x-stuff; title*=...; foo=bar; foo2*=...` || 1.822 ||
2.405 || ~1.3x ||
||= Python 3.13 (`cgi` shim, email.message gets `bytes`) =||= `cgi` =||=
`email.message` =||= ratio =||
|| `text/plain` || 0.312 ||
1.676 || ~5.4x ||
|| `text/html; charset=UTF-8; boundary=something` || 1.188 ||
3.887 || ~3.3x ||
|| `application/x-stuff; title*=...; foo=bar; foo2*=...` || 4.358 ||
2.175 || ~0.5x ||
So maybe we could indeed shortcircuit the parsing if no `;` is found in
the header line (to avoid paying the 5x slowdown), but then is unclear to
me how we could resort back to the header bytes when what we get in the
WSGI `environ` is str.
Carlton, Jake, David, any ideas?
--
Ticket URL: <https://code.djangoproject.com/ticket/36520#comment:9>
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